DESCRIPTION (adapted from the application): The Energy Balance Core Laboratory provides expertise and leading edge tools and techniques for studying nutrient utilization at the whole-body level. The services of the core laboratory are essential for many of the members of the CNRU research base. Consolidation of these tools and techniques in a single core laboratory has proven to be desirable because of the high cost of the required equipment and the extensive expertise required to keep it operating accurately. There are many sophisticated tools available for measuring components of energy balance. With rare exception, it has not been possible for individually funded investigators to maintain sophisticated, comprehensive tools for measuring energy expenditure, body composition and energy intake. The Energy Balance Core Laboratory was established to ensure that CNRU investigators have access to the best possible tools and techniques for studying energy balance. The core also provides help to investigators in choosing the tool/technique that is most appropriate for the intent and scope of their research. For example, whole-room calorimeters are highly accurate tools for measuring energy expenditure. However, their use requires accurate measurement of nutrient intake and control/measurement of energy expenditure and physical activity for several days before subjects enter the calorimeter. This is not feasible or necessary for many studies, as a metabolic cart can produce the needed information with less commitment of time and resources. In particular, this Core provides assistance with complex instrumentation that is not available for any other source within the university. It also provides training for other investigators in methods of measuring energy balance and in conducting long-term energy balance studies. This Core Laboratory offers all of the latest leading edge techniques for assessing energy balance in human subjects and in rodents. In this regard, it is one of the most comprehensive laboratories of its kind in the world. The existence of this Core Laboratory has provided the measurement of energy expenditure and body composition with a degree of accuracy and quality control that would not have been feasible for individual investigators to achieve on their own.